Sights for trench mortars and similar fire arms



June 21, 1966 c NEISIUS 3,256,608

SIGHTS FOR TRENCH MORTARS AND SIMILAR FIRE ARMS 4 Sheets-Sheet 1 Filed March 4, 1963 INVENTOR.

CHRL NE/S/US C- NEISIUS June 21, 1966 SIGHTS FOR TRENCH MORTARS AND SIMILAR FIRE ARMS 4 Sheets-Sheet 2 Filed March 4, 1963 INVENTOR.

C H RL NE 5 US June 21, 1966 c. NEISIUS 3,256,608

SIGHTS FOR TRENCH MORTARS AND SIMILAR FIRE ARMS I Filed March 4, 1963 4 Sheets-Sheet 3 Pia-8 INVENTOR.

CHR L NE S/ US June 21, 1966 c. NEISIUS 3,256,503

SIGHTS FOR TRENCH MORTARS AND SIMILAR FIRE ARMS Filed March 4, 1963 4 Sheets-Sheet 4 INVENTOR. I00 CH RL A/E/s/us United States Patent 3,256,608 SIGHTS FOR TREN CH MORTARS AND SIMILAR FIRE ARMS Carl Neisius, 3 Bernkasteler Platz, Saarbrucken, Germany Filed Mar. 4, 1963, Ser. No. 262,502 11 Claims. (Cl. 33-49) This invention relates to gun sights and is particularly concerned with a gun sight for fire arms :such as trench mortars and similar weapons which are indirectly aimed.

In the art of aiming or laying trench mortars and the like, an auxiliary target close to the fire arm is commonly employed toward which the sight is directed and which forms the zero position that determines the angularity of the fire arm, namely, the elevation and the azimuth. When using such an auxiliary target the fire arm is positioned by pivoting the sight on the gun in a direction opposite to the change in azimuth of the gun and then the gun is rotated until the auxiliary target is again visible in the sight. This same thing is done in connection with changing the elevation of the fire arm, the sight being pivoted in a direction opposite to the desired elevation of the fire arm and then the entire fire arm is tilted until a liquid level on the sight again shows a level condition for the sight while the sight remains trained on the auxiliary target.

A laying operation of this nature involves complications in that the firing orders, coming from the observation point, must be corrected by a calculation, both with respect to the elevation of the fire arm and with respect to the change in azimuth angle. Although range tables are available for this purpose, intermediate values must be obtained by interpolation which is, of course, a time consuming operation and which does not completely offset errors. The laying of such fire arms has therefore heretofore been less rapid and less accurate than would be desirable.

The errors referred to above come about for certain reasons among which are:

(a) The lateral displacement of the sight relative to the axis of the bore of the barrel of the fire arm,

(b) The distance of the sight from the horizontal axis upon which the barrel of the fire arm pivots, and

(c) The variation, which occurs in elevating the barrel, of the projection on a horizontal plane of the distance of the sight from the horizontal axis about which the barrel of the fire larm pivots when the angle of elevation of the barrel is changed.

None of these three errors is the same when the barrel .of the fire arm is swung to the right of the predetermined view of position of sighting as when the barrel is swung to the left of the zero position and to substantially the same angle.

A particular object of the present invention is to provide a sight construction particularly adapted for trench mortars and like fire arms, in which the errors referred to above are compensated so that accurate laying of the gun can be had.

Still another object of this invention is the provision of a sight arrangement for a fire arm such as a trench mortar or the like which adjusts automatically as the position thereof of the barrel on the fire arm is changed whereby to compensate for errors in laying of the gun thereby to make the aiming of the gun more accurate and more rapid.

A still further object of the present invention is the provision of a compensated sight arrangement for fire arms such as trench mortars and the like in which substantially the entire sight structure and the compensating mechanism therefore forms an integral unit easily attachable to the barrel of a fire arm.

3,256,608 Patented June 21, 1966 ice The present invention, in brief, concernsthe mounting of a gun sight on two pivots which are aligned in the direction of sighting and which are spaced apart from each other, with the positions of the said pivots relative to each other being adjustable by means of the gear by means of which the sight is changed in angularity relative to the fire arm barrel.

The present invention contemplates the adjustment of a single pivot by means of the elevating gear and the other pivot by means of the training gear and further contemplates the provision of an arrangement where one pivot remains fixed while the other pivot is simultaneously adjustable by both the elevating gear and the training gear of the fire arm.

The present invention contemplates, specifically, an optical sight for a trench mortar or a like fire arm which is offset laterally from the axis of the bore of the barrel of the fire arm and which is also offset with regard to the horizontal axis about which the barrel of the fire arm pivots as the angle of elevation of the fire arm is changed. The said sight is mounted on the barrel by means of two pivot points spaced from each other generally in the direction of sighting and also generally parallel to the axis of the bore of the firearm barrel. The respective positions of the pivot points are moveable relative to each other in conformity with the horizontal angle through which the barrel is svwng relative to a predetermined zero line of sighting and also in conformity with the angle of elevation of the barrel so that an imaginary line joining the two pivots swings relative to the axis of the barrel in such a manner as automatically to compensate or correct for discrepancies which would otherwise occur between the horizontal angles, measured from the zero line of sighting, through which the sight and the angle of the barrel rotate.

The several objects and advantages referred to above as well as still other objects and advantages of the present invention will be more apparent upon reference .to the following specification taken in connection with the accompanying drawings wherein:

FIGURE 1 is a plan view looking down on top of a trench mortar type fire arm-with the axis of the barrel extending in a vertical direction.

FIGURE 2 is a side elevational view of the fire arm of FIGURE 1.

FIGURE 3 is a plan view similar to FIGURE 1 that shows the gun laid so that the barrel has a predetermined inclination to the vertical and so that it is swung through a horizontal angle from its FIGURE 1 position.

FIGURE 4 is side elevational view similar to FIGURE 2 but shows the barrel of the fire arm in a position corresponding to the FIGURE 3 position.

FIGURE 5 is a somewhat diagrammatic perspective view showing the construction of the sight associated with the barrel of the fire arm somewhat more in detail.

FIGURE 6 is a diagrammatic view showing the geometric relationship of the various parts of the fire arm and sight arrangement in the zero position according to known methods of sighting.

FIGURE 7 shows the variation which occurs in the geometric relationship of the parts of the FIGURE 6 arrangement when the barrel of the fire arm is swung through a horizontal angle.

FIGURE 8 is a diagrammatic view showing the geometric relationship of the barrel of the fire arm and the sight and the sighting stake according to the present invention with respect to one modification of the invention.

FIGURE 9 shows the variation in the lateral angle during elevation of a fire arm barrel in conformity with known methods of sighting.

FIGURE 10 is a diagrammatic view similar to FIG- URE 9 but shows the compensation which occurs accord- 3 ing to the present invention for the error in the angle of training which is illustrated in FIGURE 9. FIGURE 11 diagramamtically illustrates a modification according to the presentinvention showing two adjustable pivots.

FIGURE 12 is a plan view of the FIGURE 11 arrangement.

FIGURE 13 is a diagrammatic view similar to FIG- URE 11 but shows a structure having one moveable pivot and one fixed pivot.

Referring to the drawings somewhat more in detail the fire arm arrangement diagrammatically illustrated in FIGURES 1 through 4 has a base on which there rests a platform 11 supported on base 10 by a pivot pin 12 which permits rotation of platform 11 about a vertical axis. Platform 11 has upstanding members 13 between which extends horizontally a pivot axis 14 on which a fire arm bar-rel 15 is pivotally mounted. The supporting arrangement for the barrel permits the barrel to be movedabout horizontal axis 14 to change the elevation of the barrel while the barrel, when so tilted, can be rotated about vertical axis 12 thereby to change the azimuth or horizontal lay of the barrel. In FIGURES 1 and 3 the barrel is shown in a zero position with the axis of the barrel extending exactly vertically and with the platform 11 in a predetermined zero position. This position is determined by sighting stake 16 which is provided at a point spaced from the gun barrel and upon which sight stake there is trained the optical sighting device indicated generally at 17. This sighting device is tiltable about a horizontal axis on the barrel of the fire arm and the optical portion thereof is also moveable in a direction transversely to the axis of the barrel of the fire arm.

In FIGURES 3 and 4, the sight has been adjusted angularly relative to the barrel axis of the barrel 15 while the portion of the sight at 18 which forms the actual sighting mechanism has been rotated in a direction transversely to the axis of the barrel so that the sighting stake 16 is still visible through the sighting mechanism.

The construction of the sight that is illustrated in FIG- URES 1 through 4 is represented somewhat diagrammatically in perspective in FIGURE 5.

In FIGURE 5 it will be noted that the barrel 15 of the fire arm has a dove-tail socket 19 provided thereon adapted for receiving the dove-tail projection 20 with which is integral a worm wheel 21. Also integral with dovetail member 20 and with gear 21 is a cylindrical portion 22 on which is rotatably supported the housing 23 of the sight mechanism.

Lock screws 24 may be provided for locking the dovetail member 20 in dove-tail slot 19 if so desired. It is important for this member and the Worm wheel 21 integral therewith to be fixed relative to the barrel of the fire arm.

There is provided in housing 23 so as to be rotatable in a wall thereof a shaft 25 that carries a Worm 26 meshing with worm wheel 21. A knurled knob 27 external of the housing is fixed to shaft 25 so that as the knob 27 is rotated the entire housing 23 of the sighting mechanism rotates about the axis of Worm wheel 21 to a position of angularity on the barrel of the fire arm. A position of this nature is illustrated in FIGURES 3 and 4, for example.

Adjustably mounted in a slot 21a extending diametrally of Worm Wheel 21 is a pivot pin 28. This pin has a flattened end part extending into a slot 29 in a block 30 that is slidable in guide ways 31 provided in the housing. It Will be evident that as knurled knob 27 is rotated the housing of the sighting mechanism will rotate relative to the barrel 15 and simultaneously slide 30 will be adjusted in its guides 31.

Carried by slide 30 is a rack 32 meshing with a pinion 33 fixed to a shaft extending through a sleeve arrangement 34 and terminating in a pinion 35 meshing with a rack 36 fixed to a second slide block 37. Slide block 37 is slidably guided in iguide ways 38 also fixedly carried within the housing of the sighting arrangement. Mounted in slide block 37 is a slot 39 extending in a direction lateral to the direction of movement of the slide block is a first pivot pin 40 having a flattened end portion adapted to slidably engage a slot 41 formed in the bottom portion of a diopter which forms the sight itself and which is identified in FIGURES 1 through 4 by reference numeral 18.

Also rotatably mounted in the wall of housing 23 of the sighting mechanism is another shaft 42 having fixed thereto externally of housing 23 a knurled knob 43 while Within the housing 23 the shaft carries a worm 44 that meshes with the worm Wheel 45. The worm wheel 45 is rotatable about the axis on which the shaft connecting pinions 33 and 35 rotates and has fixed thereto an arm 46 which, at the end remote from its connection with worm wheel 45, adjustably carries, in a slot 47, a second pivot pin 48 which is adapted to engage a bore 49 provided therefor in the bottom of sight or diopter 18.

At this point it will be evident that adjustment of knurled knob 27 to rotate the housing 23 of the sighting mechanism about the axis of worm wheel 21, will be accompanied by movement of slide 30, rotation of pinions 33 and 35, sliding-movement of slide block 37, and adjustment of pin 40 along the line of sight 50 of the diopter toward or away from pin 48. It will also be evident that rotation of knurled knob 43 will be accompanied by rotation of worm wheel 45, swinging movement of arm 46, and lateral movement of pivot pin 48 and the end of the diopter 18 which is connected thereto to effect lateral adjustment of the axis 50 of the diopter or sight.

Mounted on a vertical wall of housing 23 there is also a liquid level 51 which is employed for indicating when the sighting axis 50 of the sight or diopter 18 is exactly horizontal. Thus, after knurled knob 27 is adjusted thereby tilting housing 23 on the fire arm barrel, the liquid level 51 can be observed while the fire arm barrel is tilted about horizontal pivot axis 14 in order to restore liquid level 51 to a. zero or level setting. 7

Upon adjustment of knurled knob 43, the axis 50 of the diopter sight 18 will be swung laterally relative to the axis of the fire arm barrel, and the fire arm barrel can then be pivoted about vertical pivot axis 12 until the sighting stake 16 is again properly aligned with the sight, at which time the barrel of the fire arm will be properly laid.

With reference now to prior art practices in connection with the laying of the gun, reference may be had to FIG- URES 6 and 7. In FIGURE 6 the mortar barrel or fire arm barrel is indicated at 60 and it is pivotable about point A. A tangent sight 61 is mounted on the barrel so that it can be pivoted about a horizontal axis for adjusting the angle of elevation and also around a vertical axis for adjusting the azimuthal angle. The distance by which the vertical pivot axis of sight 61 is laterally offset from the axis of barrel '60 is indicated at b. In its FIGURE 6 position or zero position, the line of sight passing through tangent sight 61 is parallel to the axis of barrel 60. This line of sight terminates at an aiming stake 62 at point B. The perpendicular projection of the pivotal point of the barrel on the zero line of sight intersects the latter at the point C whereas point D represents the projection of B on the axis of the barrel 60.

The projection on the Zero line of sight of the distance between the pivotal point A of the barrel and the sight support is indicated by 1-2 whereas the distance between the sight support and the aiming stake is indicated by 1-1 the sum of 1-1 and 12 is indicated by L which is the distance between points B and C. It Will be evident that there is formed a triangle A, B, C having sides of the lengths L, b, and the distance from A to B. There is also formed a parallelogram A, B, C, D. The length 1--1 may be, for example, 1.5 meters when the barrel is laid in the zero direction of sighting and at elevation 1200, which is to say at an elevation of 675.

FIGURE 7 shows what occurs upon lateral swinging of the barrel 60 about the pivot point A to change the azimuth thereof. It will be observed that the angle on of swing of the sight differs considerably from the angle 6 of swing of the barrel. This is a particular point of error which is corrected by the arrangement of the present invention.

Turning now to FIGURE 8, the principle of a sight arrangement constructed according to the present invention is illustrated wherein the main parallelogram A, B, C, D is transmitted in correctly reduced scale to the sight itself. The point in FIGURE 3 corresponding to sight 61 in FIGURE 6 is indicated .at 61 while the points corresponding the corners A, B, C, D in FIGURE 1 are indicated respectively by the points A, B, C, and D. In the sight arrangement according to the present invention the point '61 actually represents the rear pivot point of the sight which is identified at 61 while point B forms the front pivot point therefor. The line of sight is thus determined by points 61 and B. It will be seen that the line of sight is displaced laterally from point A which corresponds to pivot point A in FIGURE 6 by a distance 1).

FIGURE 9 illustrates the error in the angle of training of the fire arm barrel resulting from the elevation setting. This error increases as the angle of the barrel from the vertical increases and, specifically, it increases in direct proportion to the distance from point A to point 2.

FIGURE 10 indicates the relationship in connection with a sight according to the present invention with three different elevations of the barrel and shows how the error explained in FIGURE 4 is compensated by the fact that the distance between the rear pivot point of the line of sight, at 61 and the front pivot point b is changed.

This changing may be effected by a lever, a worm, or a cam which moves the rear pivot point 61' toward and away from front pivot point b during changes in the vertical angle of the barrel.

The horizontal angle of the line of sight, namely, the

azimuth is adjusted by swinging the line of sight laterally with the principal difference being, as already indicated, that the line of sight is no longer turned only about a central pivot point, which is the case with the'FIGURE 1, 2 and 4 arrangements, but is effected by rotating the sight around a rnoveable pivot point which is adjusted in accordance with the elevation of the barrel of the fire arm. Alternatively, of course, either one or both of the pivot points for the sight could be adjusted in order to effect the two compensations referred to above. In this specific modification illustrated in FIGURE 5, it will be evident that pivot point 40 is adjusted generally in fore and aft direction of the sight or diopter18 in conformity with tilting movement of the housing 23 relative to the barrel 15, which tilting movements correspond to the angle of elevation of the barrel and lateral swinging movement of the sight or diopter 18 in order to effect adjustment of the azimuth of the gun is accomplished by swinging movement of the second pivot point 48 by rotation of worm wheel 45. It will be evident, however, that the functions of the two pivot points or pivot pins could be reversed or that they could be combined in either one of the pivot points as might be desired.

In the embodiment illustrated in FIGURES 11 and 12, the element 80 is connected with the elevating gear and it operates through a worm 81 to adjust the rear pivot element 82 in the 'fore and aft direction of the diopter or sight 18 as indicated by the arrow 83 in response to adjustment of the elevating gear to which element 80 is connected.

Element 84, on the other hand, is associated with the gear which changes the azimuth of the fire arm and pertaining to this element is a gear 85 running between the gears 86 and 87 which have a still further gear 88 therebetween. Gear "87 is connected by an arm member 89 with the front pivot point 90 of sight 18 so that as the .URES 11 and 12.

azimuth of the fire arm barrel is changed, front pivot point is swung laterally to the axis of the barrel ofthe fire arm. It will be understood that, as in connection with the modification of FIGURE 5, all of the aforementioned parts would be interconnected within a housing and that attached to the wall of the housing would be the liquid level 51 as previously described. FIGURE 11 shows the parts of the arrangement in side elevation as partly in section whereas in FIGURE'lZ the elements are shown in plan view.

In FIGURE 13 a somewhat similar arrangement is illustrated except that the element pertaining to the elevating gear is arranged to actuate a worm mechanism 101 which carries a pivot member 102 on which is mounted gear 103 which corresponds to gear 87 of FIG- Associated with gear 103 are the smaller gears 104 and 105, the latter being connected to element 106 pertaining to the azimuth changing gear and on top of gears 104 and is still another gear 107 connected by an arm 108 with front 'pivot point 109 pertaining to the sight or diopter 18. In the modification of FIGURE 13 the rear pivot point 110 for the sight or diopter is fixed and the entire adjustment of point 109 relative to point 110 is accomplished by fore and aft and lateral movements of point 109. As in connection with the other modifications the sight mechanism is all contained within or is mounted on a housing tiltably attached to the barrel of the fire arm pertaining thereto and the housing has mounted thereon the liquid level 51. In FIGURES ll, 12 and 13 the tiltability of the housing, which brings about tilting of the liquid level is indicated by the angular element 111 which tilts in response to actuation of the elevating gear 80 in FIGURES 11 and 12 and 100 in FIGURE 13. It will be understood, however, that the liquid level 51 is actually fixed to a housing which tilts relative to the barrel of the gun in response to movement of the element 80 of FIGURES 11 and 12 and element 100 of FIGURE 13 which correspond, generally, to a part of the drive train driven by knurled knob 27 in the FIGURE 5 modification.

The element 84 of FIGURES 11 and 12 and the element 106 of FIGURE 13 correspond to an element driven by knurled knob 43 of the FIGURE 5 modification.

According to the present invention there is permitted,

in addition to indirect aiming, direct sighting of remote targets in open firing position, specifically, with the sight in the neutral position which is to say with the drive to the elevating and azimuth adjusting gears disconnected. In this case the line of sight remains parallel to the barrel of the fire arm in all positions.

On account of the adjustability of the various elements, the sighting device according to the present invention is not restricted to any specific ranges or to any particular type of fire arm or mortar. For example, in the FIG- URE 5 modification it will be noted that pivot pin 28 isadjustable in worm wheel 21 while the front pivot pin 40 for the diopter or sight 18 is laterally adjustable in its supporting slide block 37 while the rear pivot pin 48 for the sight or diopter is similarly adjustable within the slot 47 in the supporting arm pertaining to the said pivot pin 48. This adjustability of these various elements permits the sighting structure to be readily adapted to a wide variety of conditions and fire arms. This increases the utility of a device according to the present invention.

This application is a continuation-in-part of my copending application, Ser. No. 649,795, filed April 1, 1957, now abandoned. I

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a sight arrangement for a trench mortar or a like fire arm; a frame, a sight pertaining to said frame, two spaced pivot points carried by said frame and engaging said sight, means for supportingly mounting said frame on the barrel of the fire arm in a position offset laterally from the axis of the bore of the barrel and also offset with respect to the horizontal axis about which the barrel pivots during a change in elevation thereof, first adjusting means operable for tilting said frame about its connection with said barrel thereby to tilt said sight in a vertical plane, means connected with said first adjusting means for adjusting the spacing of said pivots from each other, and second adjusting means operable for adjusting said pivots laterally relative to each other and without changing the spacing therebetween.

2. In a sight for a trench mortar or a like fire arm; a frame, spaced pivot members carried by the frame and defining the line of sighting, a sight device carried by said pivot members and pivotally associated with one thereof and pivotally and slidably associated with the other one thereof, means connecting said frame to the barrel of the fire arms so that the said sight device is laterally offset from the axis of the barrel and is also offset with respect to the horizontal axis about which the barrel pivots and adjustment of the elevation thereof, said means supporting the frame defining a horizontal axis of rotation for the frame, first adjusting means operable to cause rotation of the frame about said axis of rotation thereof for changing the angle of elevation of said sight device, said adjusting means being operatively connected to at least one of said pivot members and being operable during rotation of said frame to adjust the spacing between said pivot members, and second adjustable means carried by said frame and operable to adjust said pivot members laterally relative to each other to change the angle of said sight device in a horizontal plane.

3. A sight arrangement for a trench mortar or the like fire arm comprising; a frame, spaced pivot members carried by said frame and defining a line of sight, a sight device pivotally engaging one of said pivot members and pivotally and slidably engaging the other one thereof, a worm wheel rotatably mounted in said frame and adapted to be fixed to the side of the barrel of said fire arm, a worm in the frame meshing with said worm wheel, first adjusting means connected with said worm wheel and adjustable to cause rotation of said frame about the axis of said worm wheel to thereby tilt said sight device in a vertical plane, a second worm wheel in said frame, an arm connected to said second worm wheel and attached to one of said pivot members, a second worm in said frame meshing with said second worm wheel, and second adjusting means connected with said second worm and operable to rotate said second worm wheel to thereby adjust the pivot member connected thereto in a lateral direction and to adjust said sight device in a horizontal plane, at least one of said pivot members being slidably supported in said frame, and means connected to said one of said pivot members and operable in response to a tilting movement of said frame about the axis of said first worm wheel to adjust said one pivot member relative to the other one to thereby change the distance between said pivot members.

4. A sight for a trench mortar or a like fire arm comprising; a frame, spaced pivot members carried by said frame and defining a line of sighting, a sight device pivotally engaging one of said pivot members and pivotally and slidably engaging the other one thereof, a first worm wheel rotatably mounted in said frame and having means fixed thereto for attachment to the side of the barrel of the fire arm to thereby support the frame on the side of the said barrel, a first worm arranged in said frame and meshing with said first worm wheel, first adjusting means connected to said first worm and operable to tilt the frame about the axis of said first worm wheel to thereby tilt the sight device in a vertical plane, a first slide slidably mounted in said frame and supporting one of said pivot members, a second slide slidably supported in said frame, a drive pin engaging said first slide and carried by said first worm wheel in an off-center position thereon, first and second pinions drivingly interconnected with each other and also drivingly connected with said first and second slides respectively whereby tilting movement of said frame about the axis of said first worm wheel will actuate said first slide to adjust said one pivot member with respect to its spacing from the other one of said pivot members, a second worm wheel rotatable in said frame, an arm fixed to said second worm wheel and supporting said other pivot member, a second worm in said frame meshing with said second worm wheel, and second edjusting means carried by the frame and attached to said second worm.

5. A sight device for a trench mortar or a like fire arm comprising; a frame, spaced pivot members carried by the frame and defining a line of sighting, a sight device pivotally engaging one of said pivot members and slidably and pivotally engaging the other one thereof, a first worm wheel rotatably mounted in said frame and having means for fixing the said first worm wheel to the side of the barrel of the fire arm whereby said frame is rotatable about the axis of said first worm wheel, a first worm arranged in the frame and meshing with said first worm wheel, first adjusting means connected to said first worm wheel operable to tilt said frame about the axis of said first worm wheel, a pivot element carried by said first worm wheel and adjustable diametrally thereof, a first slide slidably mounted in said frame and including slot means engaged by said pivot element so that as said frame tilts about the axis of said first worm wheel said first slide can be adjusted relative to the frame, a second slide slidably guided in said frame and carrying one of the said pivot members, rack means on each of said slides, and pinions mes-hing with said rack means and-interconnected with each other whereby movement of said first slide as brought about by a tilting movement of said frame will cause movement of said second slide and the pivot member carried thereby, an arm supporting the other pivot member, a second worm wheel attached to said arm, a second worm gear meshing with said second worm wheel, and second adjusting means connected to said second worm wheel and operable to move said pivot members laterally relative to each other.

6. A sight arrangement for a trench mortar or a like fire arm comprising; a frame, spaced pivot members carried by the frame and defining a line of sighting, a sight device carried by said pivot members and pivoted to one thereof and pivotally and slidably engaging the other one thereof, means supporting said frame in a position lateral of the barrel of the fire arm and also offset with respect to the horizontal pivot axis about which the barrel pivots in adjustment of the elevation thereof, first gear means adjustable for moving said pivot members relatively in a vertical plane while simultaneously adjusting the spacing between said pivot members, and second gear means ad- ,justable for moving said pivot members laterally relative to each other without effecting any substantial change in the spacing therebetween.

7. A sight arrangement for a trench mortar or a like fire arm comprising; a frame, spaced pivot members carried by the frame and defining a line of sighting, a sight device carried by said pivot members and pivoted to one thereof and pivotally and slidably engaging the other one thereof, means supporting said frame in a position lateral of the barrel of the fire arm and also offset with respect to the horizontal pivot axis about which the barrel pivots in adjustment of the elevation thereof, first gear means adjustable for moving said pivot members relatively in a vertical plane while simultaneously adjusting the spacing between said pivot members, and second gear means adjustable for moving said pivot members laterally relative to each other without effecting any substantial change in the spacing therebetween, said means for adjusting said 3,25e,eoe

9 spacing between said pivot members comprising worm means supporting one of said pivot members and connected with said first gear for actuation thereby.

8. In a sight for a trench mortar or a like fire arm; a frame, spaced pivot members carried by said frame and defining a line of sighting, a sight device mounted on said pivot members pivotally engaging one thereof and slidably and pivotally engaging the other one thereof, said frame being mounted laterally offset from the axis of the barrel of the fire arm and also offset from the axis about which the barrel pivots as the elevation thereof is changed, first gear means operable for tilting said frame in a vertical plane thereby to move said pivot members relatively in a vertical direction, second gear means connected with at least one of said pivot members and operable for moving the pivot member connected thereto in a lateral direction relative to the other pivot member, a worm drivingly connected to said first gear means for rotation thereby, a nut on said worm, at least one of said pivot members being operatively connected with said nut for movement toward and away from the other pivot member as said worm rotates in response to the actuation of said first gear means.

9. A sight for a trench mortar or a like fire arm comprising; a frame, spaced pivot members carried by said frame and defining a line of sighting, a sight device pivotally engaging one of said pivot members and slidably and rotatably engaging the other one thereof, first gear means adjustable for tilting said frame in a vertical direction thereby to move said pivot members relatively in a vertical direction, second gear means operatively connected with said pivot members and operable for moving the pivot members relatively in a lateral direction, a worm driven by said first gear means, a nut on said worm,

and means operatively connecting said pivot members point, tilting the frame on the barrel of the gun to tilt the line of sight in a vertical direction, moving the members relatively laterally to change the line of sighting in a horizontal direction, tilting the gun barrel about a horizontal axis until the said line of sight is again horizontal, rotating the gun barrel about a vertical axis until the line of sight is again in alignment with said sighting point, and simultaneously with the tilting of said frame on the gun barrel, adjusting the distance between said members thereby to compensate for the position of the frame on the barrel laterally offset from the axis of the barrel and also offset from the horizontal pivot axis of the barrel.

11. A method of laying a trench mortar which has vertical and horizontal pivot axes associated therewith at the lower end wherein a sight device comprising a frame is attached to the side of the barrel at a point thereon spaced from the lower end thereof and said sighting device comprising spaced members defining a horizontal line of sighting which comprises; establishing a sighting mark spaced from said mortar, and horizontally aligned with the line of sight established by said members, tilting the frame on the barrel of said mortar to move said members relatively in a vertical plane thereby to tilt the line of sight established thereby in the vertical direction, moving at lea-st one of said members laterally relative to the other to change the horizontal angle of the line of sight, pivoting the mortar barrel about its horizontal supporting axis until the line of sight established by said members is again horizontal, rotating the barrel about its vertical supporting axis until the line of sight is again aligned with said sighting mark, and simultaneously with tilting of said frame on said barrel effecting adjustment of the distance between said members whereby to compensate for the position of said members laterally offset from the axis of the barrel and also offset from the said horizontal pivot axis thereof.

References @Cited by the Examiner UNITED STATES PATENTS 2,534,258 12/1950 Gallery 3349.2

ISAAC LISANN, Primary Examiner.

SAMUEL S. MATTHEWS, Examiner. 

1. IN A SIGHT ARRANGEMENT FOR A TRENCH MORTAR OR A LIKE FIRE ARM; A FRAME, A SIGHT PERTAINING TO SAID FRAME, TWO SPACED PIVOT POINTS CARRIED BY SAID FRAME AND ENGAGING SAID SIGHT, MEANS FOR SUPPORTINGLY MOUNTING SAID FRAME ON THE BARREL OF HE FIRE ARM IN A POSITION OFFSET LATERALLY FROM THE AXIS OF THE BORE OF THE BARREL AND ALSO OFFSET WITH RESPECT TO THE HORIZONTAL AXIS ABOUT WHICH THE BARREL PIVOTS DURING A CHANGE IN ELEVATION THEREOF, FIRST ADJUSTING MEANS OPERABLE FOR TILTING SAID FRAME ABOUT ITS CONNECTION WITH SAID BARREL THEREBY TO TILT SAID SIGHT IN A 